I found this curious. Colorado has had an active diving community for years--I was told about the third highest per capita (not total) statistic when I took Discover Scuba nearly 30 years ago. There has been a definite downturn of late, though. I know shops are hurting, and two just closed within the past few months.
I was also curious about your friend, the NAUI instructor and how well he is doing. The NAUI web site says there are 8 NAUI instructors in the state--last year they said there were only 2. (I suspect that is an improvement in their database more than an actual increase in instructors.) All 8 of these instructors are clustered in the Boulder/Longmont area, with the closest about 30 miles from Fort Collins. Other than a PADI shop in Broomfield that offers NAUI tech, there are no NAUI shops anywhere in Colorado. I couldn't find any web pages offering independent NAUI instruction anywhere in the state. I live in the middle of the cluster of 8 instructors, and I have never heard of any of them other than the one who does NAUI tech (a friend).
I am not challenging what you said at all. In the spirit of this thread, I am seriously interested in how your friend is getting all these students. Right now the only way that I can find NAUI instruction in the state is to go to the NAUI site, do a search for instructors, and click on the link to the name to get an email box. If that is how he is doing it, and if it is working so very well, I find it remarkable. It flies in the face of what I thought was necessary for an independent instructor to get students, and it indicates that there is no real necessity to have LDS instruction.